Justification:Halodule uninervis is a very common and widespread species. There are some localized declines and increases recorded. Overall the population is thought to be stable. This species is listed as Least Concern.

Halodule uninervis has a wide Indo-Pacific distribution. In the Pacific, it is found in southern Japan, Taiwan, the Philippines, Malaysia, Indonesia, throughout the Gulf of Thailand and along the coast of Vietnam and southern China. It occurs throughout insular Southeast Asia, northeast to the Northern Mariana Islands, Micronesia, and southeast to the Fiji Islands, as well as across northern Australia and the Great Barrier Reef.

In the Indian Ocean, it is found from Geographe Bay in Western Australia extending across the Timor Sea, the south coast of Indonesia, and to the Andaman Sea and extending around the Bay of Bengal and around India to the Malabar Coast. It ranges from the Persian Gulf to the Red Sea, south to the east coast of South Africa to Madagascar and the islands of the western Indian Ocean.

Halodule uninervis is a very common species and has a wide distribution. Studies report the species is increasing in India, decreasing in Bangledesh and stable in east Africa and the Middle East with major fluctuations in population in Australia (T.J.B. Carruthers pers. comm. 2007, Waycott et al. 2009). Globally the overall population trend is most likely stable.

Halodule uninervis is a sublittoral seagrass found from the mid-intertidal to a depth of 20 m. Halodule uninervis can grow in a range of different habitats. It is very common between 0-3 m in sublittoral lagoons and in front of reefs. It is very fast growing, colonizes rapidly and can flower prolifically. Some locations have very large seed banks. It can form dense meadows at some sites or is patchy and intermixed with other seagrass species (Skelton and South 2006), and is frequently observed on back reefs in association with larger algae (Jacobs and Dicks 1985). There is wide variability in leaf width, from 1.1-7 mm.

This species is euryhaline and can tolerate moderate disturbance (Birch and Birch 1984), and is ephemeral with rapid turn-over and high seed set (Green and Short 2003). It is considered a pioneer species, growing rapidly and surviving well in unstable and depositional environments in Eastern Australia (Green and Short 2003). It is also a pioneer species in Indonesia, usually forming monospecific beds on the inner reef flat or on steep sediment slopes in both the intertidal and subtidal zones and it has the highest density of all seagrass species in mixed (2,847 shoots/m²) as well in monospecific beds (14,762 shoots/m²) (Green and Short 2003). In Thailand, it grows in sandy or muddy sand substrates from the upper littoral to subtidal areas. This is the principal seagrass species in Kuwait, and extends along the coast of Saudi Arabia. In the Arabian Gulf, it tolerates extreme conditions with salinity varying from 38-70 ppt and temperatures of 10–39°C (inshore) and 19-33°C (offshore) (Green and Short 2003).

This species is particularly susceptible to coastal development, but it comes back quickly if conditions improve. It can also be affected by siltation and sedimentation, including burial. Other threats include destruction caused from cyclones, waves, intense grazing and infestation of fungi and epiphytes, and disease (Green and Short 2003). In some areas of its range, it is also threatened by over-exploitation and influences from activities on land (trawling activities, high hotel density in close proximity to the beach, raking, burying and removing seagrass beach cast material), use of fertilizer, oil spills and oil pollution, mining, upland clearing, destruction of mangrove forests, dredging, marina developments, eutrophication, siltation, and pollution. Also threatened by unsustainable fishing methods, illegal fisheries and fishing practices. Given its shallow water habitat, this species may also be threatened by climate change and associated increase in storm activity, water temperature, and/or sea-level rise.

Halodule uninervis is included in various conservation and management plans and programs across its range.

In the United Arab Emirates, implementation of the beginning of an effective management program that would start with baseline mapping, followed by periodic monitoring and mapping efforts. UNEP Regional Seas Programme, GCC (Gulf Cooperative Council), GAOCMAO (Gulf Area Oil Companies Mutual Aid Organisation), and other agreements which relate to environmental management and pollution controls (Green and Short 2003).

In Kenya, it is considered in the most recent management plan of the Mombasa Marine National Park and Reserve (Green and Short 2003).In Tanzania, it is within the implementation of integrated coastal zone management initiatives by IUCN including Zanzibar (Menai Bay Conservation Project), Mafia Marine Park (by WWF), and Kinondoni Coastal Area Management Programme (Green and Short 2003).

In Australia, it cannot be damaged without permit in New South Whales and Queensland, Australia. The Queensland Fisheries Act allows destruction only when a permit has been assessed and issued. Protected in Australia by either Fisheries Act or National Park or Marine Park Acts (Green and Short 2003).

In Southeast Asia is protected in the seagrass beds in Haad Chao Mai National Park, largest seagrass beds in Thailand with the highest species diversity (Green and Short 2003). The Indonesian Seagrass Committee (ISC) prepared a draft Seagrass Policy, Strategy and Action Plan to guide the management in Indonesia, and there are SeagrassNet global monitoring locations in Puerto Galera, Philippines that are now protected (Green and Short 2003).In the western Pacific islands, recognized in the need for sanctuaries and protected areas and the other concept of traditional or community management of these areas. NGOs focused on conservation and environmental protection integrated with traditional leadership and government agencies suggesting that conservation measures and the acceptance of enforcement will continue to improve (Green and Short 2003).